The invention relates to a buckle, particularly for a safety belt in an automotive vehicle, comprising a casing attached by means of a fastening arrangement to an anchoring point on the vehicle, a latch that can be brought into locking engagement with an opening in a tongue, an ejector spring for the tongue and a bias spring for a push button that can be brought into engagement with said latch.
Numerous designs for buckles of safety belts for automotive vehicles are known. Many buckles have the aforecited characteristics and are constructed so that the latch is biased in the locked or engaged position. Until now, it has always been thought that this provision enhances the reliability of the locking engagement.
It is also important, however, to consider the emergency case in which the release of the tongue from the buckle must occur instantly and smoothly. Moreover, one must keep in mind the normal functions of the buckle and particularly, in normal use, the possibility of smoothly removing the tongue by pressing a push or press button.
The object of the invention is to improve a buckle of the aforecited type so that when, in the normal position, the push button is not depressed, the locking engagement with the tongue is absolutely reliable and yet the unbuckling is substantially facilitated compared to conventionally designed buckles. In other words, when in known buckles, in the normal position with the push button not depressed, the latch was in locked engagement, unbuckling until now was difficult. In known buckles, until now depressing the push or press button did not necessarily ensure smooth movement of the latch out of the opening of the tongue which would result in instantaneous release of the safety belt system. Moreover, until now there has also existed the difficulty that after apparent locking it was possible, under a certain load, to pull the tongue from the buckle even without pressing the push button.
According to the invention these drawbacks are eliminated by providing a latch which is pivotable on a pivotal axis perpendicular to the direction of insertion of the tongue and is fixed in the casing and which is biased in the unlocked position by the bias spring, said latch, when the bias spring is at least partly extended, being held in locked engagement with the tongue by a reinforcing member that moves together with the push button. A novel and surprising feature of the buckle of the invention is the fact that, in the open position, the latch is in a stable position because the button return spring at the same time also exerts pressure, in the release direction, on the latch that is pivotable on a pivotal axis. This ensures that, after actuating the push button and unbuckling, the buckle will remain in the open, i.e., disengaged or unlocked position. The buckle of the invention saves one the effort which in conventional buckles is needed to move the latch from its normally closed position into the open position so that the tongue can be inserted into the buckle. By contrast, the buckle of the invention is normally in the open, receiving position and, by insertion of the tongue, is readily brought into the engaged position.
According to the invention, it is also advantageous that the supporting end of the latch, disposed near the reinforcing member, is provided on the inside of the push button and, when the push button is depressed, can be moved into an internal downwardly opening cavity. Another advantage of the invention lies in the fact that the reinforcing member is shaped in the form of a crossbar fastened to the underside of the push button, the longitudinal direction of said member being parallel to the pivotal axis of the latch. This reinforcing member, which in a preferred embodiment has the form of a crossbar, for example a square bar, is freely movable relative to the latch, and, similarly, the push button is freely movable back and forth over some distance, relative to said supporting end of the latch, in the direction of insertion of the tongue. In other words, this reinforcing member bearing the supporting end of the latch is preferably held by the push button so that it moves therewith. The surprising advantage of the invention is that only in a certain position, namely when the button return spring is in the extended position or, in other words, when the push button is in the normal position of rest, can the supporting end reach the supporting position opposite the reinforcing member and press the latch into locking engagement holding it there. In other words, said reinforcing member in the push button holds the latch in locking engagement safely and reliably against the torque generated by the bias spring and which tends to pivot the latch into the unlocked position. When, by actuating the push button, the reinforcing member is moved out of the cited certain position for a distance such that the supporting end of the latch is essentially completely pushed down and away from the reinforcing member, the supporting end can move into the downwardly opening internal cavity of the push button without encountering any resistance; in other words, the latch then pivots on the pivotal axis and into the unlocked or release position.
According to the invention, it is also advantageous that the other end of the latch which is opposite the supporting end is provided with an opening intended to receive a guide pin for the push button, said pin guiding the push button and the bias spring which abuts against the other end of the latch. In this manner, not only is the bias spring guided in the correct direction, but at the same time the push button is also guided in the direction in which it moves, without the need for special extra parts which would add to the cost of the buckle.
Another useful embodiment of the invention is characterized by the fact that the pivotal axis of the latch is located near the other end, i.e., the end containing the opening, forming a long and a short lever arm. In this manner, it is possible to adjust the length of the lever arms depending on the forces desired. By the aforecited provisions, the force required to pivot the latch into locking engagement when the tongue is inserted into the buckle is kept conveniently small. In other words, in fastening the belt, the car occupant feels only an insignificant resistance and yet the forces acting when the latch is pivoted back into the release position are sufficient so that when the push button is actuated, i.e., when the reinforcing member is moved relative to the supporting end, the latch is immediately pivoted into the unlocked position.
In another advantageous embodiment of the invention, the latch has an elongated shape extending over from about one-half to three-quarters of the length of the buckle casing, and when viewed in longitudinal section has the shape of a rocker with upturned U-shaped ends. This design was found to be particularly reliable. A latch thus shaped can be used at the same time for locking as well as to provide the guide hole for the push button pin and as a stop for the button return spring.
It is also advantageous, according to the invention, that a holding arm protrudes from the underside of the latch for a distance equal to the thickness of the tongue at a point such that in the locked position said holding arm lies exactly in the opening of the tongue. A latch of this design is technically simple and economical to produce without affecting the forces generated by the latch in a simplified buckle.
As a result of the provisions of the invention, the latch cannot pivot when the reinforcing member, preferably in the form of a crossbar, is arranged above the supporting end of the latch. This reinforcing member moves together with the push button and is preferably located in an opening of rectangular cross-section in the push button base.
After the tongue has been inserted, i.e., after the car occupant has fastened the belt, the belt can be unbuckled by actuating the push button thereby moving the reinforcing member in relation to the supporting end of the latch. In this manner the latch pivots, releases the tongue and remains in the open position. This pivoting motion is imparted by the tongue which is ejected by the ejector spring. Tension on the belt strap can possibly also pull the tongue out thus causing the latch to pivot into the open position. This swiveling motion toward the open position is also favored by the partial extension of the bias spring which causes the latch to pivot.
The push button and the reinforcing member remain in this advanced position when the buckle is opened. The latch is kept in the open position by the button return spring which functions between the push button and the other end of the latch. When the tongue is taken out of the buckle, the latch is also supported by the ejector spring.
Reinserting the tongue into the buckle by pressing the small front edge against a sliding hook generates a reverse torque about the pivotal axis of the latch which pivots said latch back into the closed position. This brings the holding arm in locking engagement with the opening in the tongue. The reinforcing member and the push button can now return to their starting position, the contact between the supporting end of the latch and the reinforcing member once again keeping the latch from pivoting.